CVE-2026-4265

| EUVD-2026-12425 MEDIUM
2026-03-16 Mattermost GHSA-xpvf-6qcc-9jqc
4.3
CVSS 3.1
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CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

Lifecycle Timeline

4
Patch Released
Mar 31, 2026 - 21:13 nvd
Patch available
Analysis Generated
Mar 16, 2026 - 13:00 vuln.today
EUVD ID Assigned
Mar 16, 2026 - 13:00 euvd
EUVD-2026-12425
CVE Published
Mar 16, 2026 - 12:07 nvd
MEDIUM 4.3

Tags

Authentication Bypass Mattermost

Description

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to validate team-specific upload_file permissions which allows a guest user to post files in channels where they lack upload_file permission via uploading files in a team where they have permission and reusing the file metadata in a POST request to a different team. Mattermost Advisory ID: MMSA-2025-00553

Analysis

This vulnerability in Mattermost allows guest users to bypass team-specific file upload permissions through a cross-team file metadata reuse attack. Affected versions include Mattermost 11.3.0, 11.2.x up to 11.2.2, and 10.11.x up to 10.11.10. …

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Remediation

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Monitor vendor channels for patch availability.

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Priority Score

22
Low Medium High Critical
KEV: 0
EPSS: +0.0
CVSS: +22
POC: 0

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CVE-2026-4265 vulnerability details – vuln.today
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